Semiconductor device applications have experienced significant scaling (reduction in size) over recent years, with continued scaling desirable for a multitude of applications. Often, a reduction in size of semiconductor devices has presented challenges to the performance of such devices. For instance, the drive current is often lower than that required at power-supply voltages for small (e.g., sub-45 nm) nodes. Addressing issues such as the short-channel effect and subthreshold leakage current often requires tight control of intricate vertical and lateral channel doping profiles, often involving heavy doping, shallow source/drain junctions and ultrathin gate dielectrics. Such approaches to addressing such issues can adversely affect carrier mobility, subthreshold swing and series resistance.
Many semiconductor devices generally exhibit channel regions that are switched by an electrode to facilitate the flow of current. Generally, high mobility in the channel region is desirable for such current flow. In addition, low power consumption and small size have also been desirable for a variety of applications.
High-mobility materials like Germanium, Germanium-rich (Ge-rich) materials, InSb (Indium Antimonide), InAs (Indium Arsenide), strained Germanium and strained Silicon-Germanium materials (e.g., SixGe1-x) have been considered as desirable for their mobility. However, most higher mobility materials have a significantly small bandgap relative, for example, to Silicon and correspondingly suffer from relatively high tunnel current leakage (e.g., via band-to-band-tunneling, or BTBT) and short-channel effects. Such tunneling current tends to limit the scalability of semiconductor devices.
These and other characteristics have been challenging to the design, manufacture and use of semiconductor devices.